Volume 431, Number 1, February III 2005
|Page(s)||235 - 251|
|Section||Interstellar and circumstellar matter|
|Published online||02 February 2005|
The internal dynamical equilibrium of H II regions: A statistical study
Instituto de Astrofísica de Canarias, C. Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain e-mail: [mpastor;corrado]@ll.iac.es
2 Consejo Superior de Investigaciones Científicas (CSIC), Spain e-mail: email@example.com
3 Dpto. de Física Teórica y del Cosmos, Facultad de Ciencias, U. de Granada, Avda. Fuentenueva s/n, 18071 Granada, Spain e-mail: firstname.lastname@example.org
4 Isaac Newton Group of Telescopes, Apartado de Correos 321, 38700 Santa Cruz de La Palma, Canarias, Spain
5 Observatorio Astronómico Nacional (UNAM), Apartado Postal 877, Ensenada, B.C., México e-mail: email@example.com
Accepted: 14 October 2004
We present an analysis of the integrated Hα emission line profiles for the H ii region population of the spiral galaxies NGC 1530, NGC 6951 and NGC 3359. We show that ~70% of the line profiles show two or three Gaussian components. The relations between the luminosity () and non-thermal line width () for the H ii regions of the three galaxies are studied and compared with the relation found taken all the H ii regions of the three galaxies as a single distribution. In all of these distributions we find a lower envelope in log . A clearer envelope in is found when only those H ii regions with are considered, where is a canonical estimate of the sound speed in the interestellar medium. The linear fit for the envelope is where the Hα luminosity of the region is taken directly from a photometric H ii region catalogue. When the Hα luminosity used instead is that fraction of the H ii region luminosity, corresponding to the principal velocity component, i.e. to the turbulent non-expanding contribution, the linear fit is , i.e. unchanged but slightly tighter. The masses of the H ii regions on the envelope using the virial theorem and the mass estimates from the Hα luminosity are comparable, which offers evidence that the H ii regions on the envelope are virialized systems, while the remaining regions, the majority, are not in virial equilibrium.
Key words: ISM: H II regions / ISM: kinematics and dynamics / galaxies: individual: NGC 1530, NGC 6951, NGC 3359 / galaxies: ISM
© ESO, 2005
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.